The several hundred members of the Eukaryotic protein kinase superfamily characterized to date share a similar catallytic domain structure, consisting of 12 conserved subdomains. Recently, a new class of protein kinases, represented by eukaryotic elongation factor-2 kinase, has been discovered with completely different structure. We are attempting to identify the ATP binding site of this new class of protein kinase and also gain an understanding of its regulation via phosphorylation.